Wave energy recovery device

ABSTRACT

A device for recovering the energy of sea waves, which comprises at least one floating structure intended to float on the surface of the water. Said floating structure carries at least one member ( 2 ) suspended above the surface of the water, the structure of which is designed to generate recoverable energy through the variation in height of the surface of the water relative to said member, under the effect of the ascending and descending movement of the waves. Application to recovering wave energy.

This invention relates to a device for recovering the energy of sea waves over an expanse of water, such as at sea.

Currently, energy consumption is primarily based on non-renewable energies such as oil, gas, coal and nuclear. In light of the depletion of the reserves of these energies and/or of the pollution that is generated in using them, it is sought to diversify the sources of energies, by turning in particular towards renewable energies.

In this context, one solution consists in using the energy coming from the sea, more precisely in terms of currents, waves or tides.

As such, the energy from waves is nothing less than a particular form of solar energy. The sun heats the different atmospheric layers unequally which causes air currents (winds) which are then responsible by friction for the movements which animate the surface of the sea (currents, waves).

The waves created by the wind on the surface of the seas and oceans transport energy. When they arrive on a floating or coastal obstacle they can relinquish a portion of this energy which can be transformed into electric current. It is where the winds are the strongest, between 40° and 60° latitude, that the power of the waves is maximum.

Consequently, energy from waves has a very high potential of power. As such, the average power transported by the waves is given in kW per linear meter. It is proportional to the period of the waves (duration that separates the arrival of two successive wave crests) and to the square of the height of the wave (distance between the trough and the crest). For example this potential is 63 kW/m off the coast of Ouessant, an average of 50 kW/m on the Atlantic coast and 8 kW/m in the Mediterranean.

Energy from waves is also characterized by the energy that arrives during one year over a linear meter of installation. For example, on the French Atlantic coast this potential is 420 MWh/m. Over 1000 km of Atlantic coast the annual energy transported by the waves is 420 TWh, which is of a magnitude of the total electrical energy consumed in France each year.

However, this total resource cannot be fully used in particular in light of the technical limitations and natural or legal limitations that reduce the domain that can be used.

Numerous devices have already been proposed, which can be classed into two major categories: coastal devices and open sea devices.

The first use the breaking waves, and the second use the variations in the level of the sea during the passage of the waves. The first are easy to build and maintain but their output is clearly not as good as the open sea devices which use more powerful and more regular waves.

As such, EP 1 295 031 discloses a device based on the movement of a buoy, the device comprising an exterior round floater surrounding an interior floater, these two floaters being connected to one another by means of linking comprising in particular hydraulic cylinders making it possible to recover the energy of the movement between the two floaters and having furthermore an immersed body.

A mobile cylinder is also known (the floater) filled with air that slides on a cylinder fixed to the sea bottom. In the absence of waves the floater is balanced. When the top of the wave passes over the floater the overpressure drives the floater downwards. In the trough of the wave the depression cause the floater to go back up. The comings and goings of the floater in relation to the fixed cylinder causes a linear dynamo that produces electric current. This device however has the disadvantage of having to be fixed in part to the sea bottom.

This invention therefore has for purpose to propose a device for recovering the energy of the waves of which the simpler structure facilitates its use and implementation.

As such, this invention has for purpose a device for recovering the energy of sea waves, comprising at least one floating structure, intended to float on the surface of the water, characterized in that said floating structure bears at least one member suspended above the surface of the water of which the structure is designed to generate a recoverable energy through the variation in height of the surface of the water in relation to said member, under the effect of the ascending and descending movement of the waves.

Very advantageously, a device according to the invention makes it possible through the cooperation of the structure of said member with the surface of the water to recover an energy that is up to twice or more than that of the height of the wave and/or that of the speed of the vague.

Advantageously, according to a form of an embodiment, the floating structure is more preferably comprised of at least two floating elements such as beams extending substantially in parallel to one another, one in the front and the other in the rear and between which extends substantially protruding upwards, at least one post forming a bridge between said floating elements, the at least one suspended member being fixed on said post in such a way as to extend substantially perpendicularly to the floating elements and substantially at equal distance from the latter.

More preferably, the floating structure has a length defined by the length of the front and rear floating elements, less than the spacing between said front and rear floating elements, said front and rear floating elements being positioned parallel to the waves, in optimal operating position on the surface of the water, the axis connecting the floating elements being as such substantially perpendicular to the waves.

More preferably, the spacing between the front and rear floating elements can be adjusted using any appropriate means. In this way, it is possible to adapt the spacing between the front and rear floating elements in such a way that it corresponds to the wavelength of a wave, a wave being as such imprisoned between the two floating elements. Of course, the spacing between the floating elements can be fixed.

Preferably, the floating structure further comprises appropriate means in order to allow for the positioning of said structure on the surface of the water in optimal position, i.e. in such a way that the front and rear floating elements are parallel to the waves.

As such, these means can be comprised of at least one keel borne by the floating structure, more preferably the keel being provided connected to each floating element.

Such means can also be comprised of at least one wind resistance element borne by the floating structure orienting said floating structure facing the wind in such a way that the floating elements are parallel to the waves.

According to an alternative embodiment of the invention, the floating structure is comprised of at least four floating elements such as floating beams, connected to said member.

Likewise, according to another alternative embodiment, the floating structure is comprised of at least four floating elements such as floating elements borne at the end of posts, said floating elements being connected to said member by said posts, with two floating elements in the front and the other two in the rear.

As such, two floating elements are defined borne by posts, in the front and two in the rear, the alignment of the front floating elements and the alignment of the rear floating elements being parallel in relation to one another, and in optimal operating position of the device, parallel to the waves.

Preferably, at least one of the front floating elements of said floating structure, can be oriented in relation to a vertical axis of said floating element in such a way that said front floating element cannot extend in parallel to the other front floating element, the axis that connects them being always substantially parallel to the waves.

This is in particular the case when the floating elements have for example an elongated shape such as a beam.

More preferably, the floating structure of the device according to the invention is designed in order to be able to be attached to a buoy, an anchor; but it can also be towed by a boat, propelled or self-propelled or otherwise from the front in order to facilitate its positioning facing the waves so that the front and rear floating elements or their alignment are parallel to the waves.

According to a first embodiment of the invention, said suspended member borne by said floating structure comprises a floating element intended to float on the surface of the water, this floating element being connected by at least one flexible connector element such as a chain, sling, cable, to means that are designed to generate energy either in the electrical form or in the form of a compressed fluid, under the effect of at least the traction, exerted on the flexible connector element by at least the descending movement of the floating element under the effect of the movement of the waves.

More preferably, the means of generating energy in the form of electric current are such that a dynamo of which the driving in rotation in order to generate electrical energy intervenes under the effect of a traction exerted by the floating element on the flexible connector element for example rolled on the dynamo. It furthermore makes it possible to produce electrical energy directly from the movement of the waves.

The energy of the waves can be recovered, at least during the traction exerted on the flexible connector element, by means of generating energy in the form of compressed fluid, releasable through conventional means either to generate electrical energy or through the use of the compressed fluid in the form of pneumatic, hydraulic energy.

According to a second embodiment, said member defines at least in part an enclosure of which the volume is variable according to the height of the surface of the water, therefore of the waves, with the compression of a fluid enclosed within said volume generating a recoverable energy.

More preferably, the member borne by the floating structure is an enclosure having an open lower end and a closed upper end, said enclosure being fixed to the floating structure on the side of its closed end in such a way that its open end is immersed, the water entering into the volume defined by said closed cylinder, in such a way that, under the effect of the waves, the height of the water in the enclosure defined as such can vary causing the variation of the volume of said enclosure and generating in particular a compression of the air enclosed within, which can then be recovered in order to generate energy.

According to an alternative of this form of embodiment, a floater engaged in said enclosure can be provided making it possible to regulate the rise of the water and the pressurization of the air in said enclosure. In addition, this floater also makes it possible to recover the energy generated by the descending of the weight of said floater as soon as the water descends faster than it does.

The compressed air in said enclosure can be used directly in the form of pneumatic energy or be used to generate electricity. This recovered compressed air is indeed then recovered and used by appropriate conventional means.

Such a device according to the invention can advantageously be used at sea to allow in particular the supplying in electricity of sites such as fish-breeding farms or for any other use at sea and over expanses of water on land (lake, river, stream, pond) requiring an electrical, hydraulic and/or pneumatic energy.

Furthermore, still more preferably, the floating structure comprises at least one wind turbine more preferably of fixed orientation. The energy of the wind at the level of the floating structure can as such also be recovered in order to convert it into energy, in particular into electrical energy.

The invention shall be described now in more detail in reference to the drawing wherein:

FIG. 1 a shows a transversal cross-section of a first example of an embodiment of the device according to the invention, with the wave being high between the floating elements of the floating structure;

FIG. 1 b shows a view according to FIG. 1 a with the wave being low between the floating elements of the floating structure;

FIG. 1 c shows a top view of the device in FIG. 1 a;

FIG. 1 d shows a cross-section of an alternative of the device in FIG. 1 a;

FIG. 2 shows a cross-section of a second alternative embodiment of the device in FIG. 1 a;

FIG. 3 shows a cross-section of a third alternative embodiment of the device in FIG. 1 a;

FIG. 4 shows a cross-section of a fourth alternative embodiment of the device in FIG. 1 a;

FIG. 5 shows a transversal cross-section of a fifth alternative embodiment of the device in FIG. 1 a;

FIGS. 6 a and 6 b show respectively a cross-section view and a top view of a second example of an embodiment of a device according to the invention;

FIGS. 7 a and 7 b show respectively a cross-section view and a top view of an alternative of the device in FIGS. 6 a and 6 b;

FIG. 8 a shows a transversal cross-section of a third example of an embodiment of a device according to the invention, with the wave being high between the floating elements of the floating structure of the device;

FIG. 8 b shows a cross-section of the device in FIG. 8 a; with the wave being low, between the floating elements of the floating structure of the device;

FIG. 8 c shows a top view of the device in FIG. 8 a;

FIG. 8 d shows a cross-section at the level of the line A-A in FIG. 8 c, and

FIG. 9 shows an alternative embodiment of the device shown in FIGS. 8 a to 8 d.

The device according to the invention shown in FIGS. 1 a, 1 b and 1 c shows a floating structure comprised of two floating elements 1, 1′ such as beams extending substantially parallel in relation to one another and to the waves and between which extend posts 3 forming a bridge between said floating elements 1, 1′.

A member 2 such as a fixed enclosure suspended on each post 3 extends substantially perpendicularly at the level of the sea to said beams 1, 1′ and substantially at equal distance from the latter. This cylindrical circular section enclosure closed at one end 2 a is fixed to a post 3 at the level of said closed end 2 a while its open end is immersed. This member 2 thus defines an enclosure of which the volume A is variable according to the waves, i.e. to the level of water entering into said enclosure 2.

In such a way as to be able to best recover the energy of the waves, the optimal positioning of the device is such that the floating elements 1, 1′ are located parallel to the waves, the one 1 being at the front and the other 1′ at the rear in the direction of the waves shown by the arrow H in FIGS. 1 a and 1 b.

More preferably, the spacing between the floating elements 1, 1′ corresponds to one wavelength of a wave, a wave being as such imprisoned between the two floating elements 1, 1′, as can be seen in FIG. 1 a.

In FIG. 1 a, the floating elements 1, 1′ are thus in wave troughs and the member 2 located between said floating elements 1, 1′ is located approximately at the level of a wave crest in such a way that the level of water in the enclosure is maximal, which generates the reduction of the volume A′ and thus the compression of a fluid such as the air enclosed within said volume. This compression of the air generates a recoverable energy. In particular, the compressed air exits said compression chamber A′ formed as such through a non-return valve 6 provided on the end 2 a of the enclosure which allows air to pass only after a certain pressure has been reached in said compression chamber A′ formed as such.

Then, when the member 2 is located in a wave trough, the level of the water drops back down in the enclosure which then returns to a normal volume A. As such, a theoretical travel is obtained that is double that of the height of the waves (cf. FIG. 1 b).

In order to increase the stability of the floating structure, it can be considered that the beams 1, 1′ enclose a certain quantity of water.

Any addition means of maintaining the enclosure 2 such as slings or rigid arms 4 can be provided.

In FIG. 1 d, a device according to FIG. 1 a is shown and further comprises a second member 5 defining an enclosure of which the volume is variable under the effect of the waves. This member 5 is present in the form of an enclosure with tapered wall forming a funnel and extending from a beam 1 perpendicularly to the latter on the surface of the water. A non-return valve 6′ is also provided in order to recover the compressed air. The recovering of energy is as such further improved. This member 5 can be installed for example between two enclosures 2.

FIG. 2 shows an alternative embodiment of a device in FIG. 1 a wherein the member 2 is furthermore provided with a floater 7 inside the enclosure defined by said member 2. This floater 7 makes it possible to regulate the rise of the water in the enclosure.

In FIG. 3, the member 2 further comprises an orifice in its upper portion through which can be engaged a rod 7 b arranged protruding from a floater 7.

In FIG. 4, the member 2 also has a tubular protuberance 2 c wherein is housed the rod 7 b arranged protruding from the floater 7. AZ first enclosure A and a second enclosure B is thus defined, the chamber A defined as such can be at atmospheric pressure and the chamber B can be at an additional pressure.

FIG. 5 shows an alternative embodiment of the floating structure wherein tubular posts or other 30 extend between the beams 1 on either side of a member 2 in order to maintain it.

At least one non-return valve 6 is provided on each member 2 (FIGS. 2, 3, 4, 5) in order to allow for the passage of the air after a certain pressure has been reached in said compression chamber formed in each enclosure 2.

The floating structure can also be carried out in such a way as to be organized around the member defining the enclosure, the floating structure thus comprising the suspended member. As can therefore be seen in FIGS. 6 a and 6 b, for example four beams 10, 10′ extend perpendicularly to said cylinder 2 forming a cross-shaped floating structure. The spacing between the beams 10, 10′ can be adjusted by all appropriate means.

Alternatively, posts 8 extend from the enclosure 2 and are provided with floating elements 9, 9′ at their ends, as can be seen in FIGS. 7 a and 7 b.

Here also, the positioning for optimal operation of the device consists in having two beams 10 at the front and two beams 10′ at the rear or two front floating elements 9 and two rear floating elements 9′ in relation to the direction of the waves.

As such, the two floating elements 9 substantially aligned at the front one in relation with the other and the two floating elements 9′ substantially aligned at the rear one in relation with the other will be respectively substantially parallel to the waves in optimal operating position, the device comprising appropriate means in order to allow for its optimal positioning such as those mentioned hereinabove. However, one of the front floating elements 9 can be oriented in relation to a vertical axis of said floating element 9 in such a way that said front floating element 9 cannot extend in parallel to the other rear floating element 9′, their alignment remaining more preferably parallel to the waves.

Furthermore, the spacing between the front floating elements 9 and the rear floating elements 9′ can be adjustable or fixed.

More preferably, the length of the floating structure defined by the distance between the front or rear floating elements can be greater than the spacing defined between the front 9 and rear 9′ floating elements.

In the example of the embodiment shown in FIGS. 8 a to 8 d, the post 11 extending between the beams forming floating elements 1, 1′ is erected substantially to the vertical forming an inverted V.

The member borne by the floating structure is comprised of a piston 12 of which the free end is fixed to the floating structure, in this case to the tip of the post forming a bridge of the floating structure. The other end forming a piston is engaged in a cylinder 13, said cylinder 13 being connected at its other end to a member 14 such as a float counterweight conformed to float on the surface of the water. This float counterweight 14 is arranged in order to exert almost permanently a force of traction towards the surface of the water. It is more preferably positioned closer to the front floating element 1 of the floating structure.

Likewise, on the floating structure can be provided means making it possible to hoist the floater 14 above the surface of the water during storms. Indeed, it is preferred to shut down the device according to the invention in the event of a storm from a standpoint of resisting the waves as well as resisting the air.

As such, when the position is at the crest of a wave, the cylinder 13 extends around the rod of the piston 12 (see FIG. 8 a). When passage is made into a wave trough (FIG. 8 b), the cylinder 13 driven by the floater 14 which is sufficiently heavy to still float on the surface of the water or air slides along the piston 12 and this sliding allows for the driving of a dynamo, for example, by the intermediary of a chain on which the cylinder exerts a traction. The piston and the cylinder serve advantageously to guide the cable, in order to limit the swinging movement of the float counterweight 14.

Inversely, the member borne by the floating structure is comprised of a cylinder of which one end is fixed to the apex of a post forming a bridge of the floating structure and of which the other end engaging on a piston, said piston being connected at its free end to a member such as a float counterweight, conformed to float on the surface of the water, said piston during its sliding along the cylinder under the effect of the waves actuating a member generating electrical energy, for example.

In order to stabilize the floating structure, spacers 15 are also provided between the beams 1 and a spacer 16 between the tops of the posts 11 or any other appropriate means.

In this embodiment, the floating structure can be comprised of two boats instead of floating beams connected by a bridge structure in the shape of an inverted V, the rod and the cylinder being connected to a third boat forming the floater 14.

The elements comprising the device according to the invention are made from all appropriate materials in particular composite materials, steel, aluminum, etc.

In the alternative shown in FIG. 9, the floating structure comprises a member 25, 25′ forming a funnel arranged to channel the waves into a corridor closed from underneath using a plate 27 extending from a front floating element 1 towards the space between the two floating elements 1, 1′ of the floating structure. This member forming a funnel is more preferably comprised of lateral walls 25 extending from the floating elements 1 towards the suspended member, here the floater 14, vertically in relation to the plate 27 in order to define a channel that shrinks until the floater 14 and that then re-enlarges 25′ towards the rear floating element 1′, thus increasing the height of the waves on float counterweight 14 or on an enclosure 2. This member 25, 25′ is furthermore adjustable.

More preferably, the floating structure is designed in order to be able to be attached, propelled or self-propelled from the front, in order to facilitate its positioning facing the waves in such a way that the floating elements 1, 1′; 9, 9′ are always at a maximum parallel to the waves.

Of course the invention is not limited to the examples described but covers all of the forms of embodiment mentioned by all of the claims. 

1. Device for recovering the energy of sea waves, comprising at least one floating structure, intended to float on the surface of the water, characterized in that said floating structure bears at least one member (2, 14) suspended above the surface of the water of which the structure is designed to generate a recoverable energy through the variation in the height of the surface of the water in relation to said member, under the effect of the ascending and descending movement of the waves.
 2. Device according to claim 1, characterized in that the floating structure comprises at least two floating elements (1, 1′) extending substantially in parallel in relation to one another, one in the front (1) and the other (1′) in the rear, and between which extend substantially protruding upwards, at least one post (3, 30, 11) forming a bridge between said floating elements (1, 1′), at least one member (2) being fixed on said post in such a way as to extend substantially perpendicularly to said floating elements (1, 1′).
 3. Device according to claim 1, characterized in that the floating structure comprises at least four floating elements (10, 10′), connected to said member (2).
 4. Device according to claim 1, characterized in that the floating structure comprises at least four floating elements (9, 9′) borne at the end of posts (8), said floating elements (9, 9′) being connected to said member (2) by said posts (8), the four floating elements comprising two front floating elements (9) and the two rear floating elements (9′).
 5. Device according to claim 4, characterized in that, at least one of the front floating elements (9) can be orientated in relation to a vertical axis of said floating element (9) in such a way that said floating element (9) cannot extend in parallel to the other floating element (9).
 6. Device according to claim 2, wherein the spacing between the front (1; 9) and rear (1; 9′) floating elements is adjustable.
 7. Device according to claim 2 wherein the spacing between the front and rear floating elements (1, 1; 9, 9′) is fixed.
 8. Device according to claim 2, wherein the floating structure further comprises means for positioning said structure on the surface of the water in such a way that the front and rear floating elements (1, 1; 9, 9′) are parallel to the waves.
 9. Device set forth in claim 8, wherein the positioning means comprise at least one keel borne by the floating structure.
 10. Device set forth in claim 8, wherein the positioning means comprise at least one wind resistance element borne by the floating structure orienting said floating structure when it is on the surface of the water facing the wind in such a way that the front (1; 9) and rear (1; 9′) floating elements are parallel to the waves.
 11. Device according to claim 1, wherein the member borne by said floating structure comprises a floating element (14), intended to float on the surface of the water, this floating element being connected by at least one flexible connector element to means for generating energy at least under the effect of the traction, exerted on the flexible connector element at least by the descending movement of the floating element under the effect of the movement of the waves.
 12. Device according to claim 11, wherein the member borne by the floating structure comprises a piston (12) of which a free end is fixed to the floating structure and of which an other end forming a piston (12) is engaged in a cylinder (13), said cylinder (13) being connected at its other end to a member (14) conformed to float on the surface of the water, said cylinder arranged so as to, during its sliding along the piston under the effect of the waves actuating a member generating energy such as in the electrical form, in the form of compressed fluid.
 13. Device according to claim 11, wherein the generating means comprise a dynamo which is driven in rotation to generate electrical energy by the effect at least of a traction exerted by the floating element on the flexible connector element rolled on the dynamo.
 14. Device according to claim 1, wherein said member defines at least in part an enclosure of which the volume is variable according to the height of the surface of the water, therefore of the waves, with the compression of a fluid enclosed within said volume generating a recoverable energy.
 15. Device according to claim 14, wherein the member borne by the floating structure is an enclosure (2) having an open lower end and a closed upper end (2 a), said enclosure (2) being fixed to the floating structure on the side of its closed end (2 a) in such a way that its open end is immersed, the water entering into the volume defined by said closed enclosure, in such a way that, under the effect of the waves, the height of the water in the enclosure defined as such can vary causing the variation in the volume of said enclosure and generating a compression of the air enclosed within that is then recoverable in order to generate the energy.
 16. Device according to claim 15, wherein a floater (7) is engaged in said enclosure making it possible to regulate the rise of the water and the pressurization of the air in said enclosure.
 17. Device according to claim 1, wherein it further comprises a member (5) having in the form of an enclosure with tapered wall forming a funnel and extending from a floating element (1′) perpendicularly to the latter on the surface of the water, making it possible to recover the compressed air by the height and the speed of a wave, directly or by the intermediar of a piston, using a non-return valve (6′).
 18. Device according to claim 1, wherein the floating structure comprises a member (25, 25′) forming a funnel arranged to channel the waves into a corridor closed from underneath using a plate (27) extending from a front floating element (1) towards the space between the two floating elements (1, 1′) of the floating structure, said member forming a funnel being comprised of lateral walls (25) extending from the floating elements (1) towards the suspended member (14), vertically in relation to the plate (27) in order to define a channel that shrinks to said member (14) and that then re-enlarges (25′) towards the rear floating element (1′), this member (25, 25′) being furthermore adjustable.
 19. Device according to claim 1, wherein the floating structure is designed in order to be able to be attached, towed, propelled or self-propelled from the front, in order to facilitate its positioning facing the waves so that the front and rear floating elements are parallel to the waves.
 20. Device according to claim 1, wherein the floating structure further comprises at least one wind turbine of a fixed orientation in order to produce electricity. 